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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 828 · 40 questions
TalentJR

How to do it in your head (Guess, divide, average): Division: round the divisor to the nearest ten and find the closest multiple of it. Square root: guess the nearest whole root, then divide the number by your guess. Average the guess and the answer of the division, and round to 1 decimal place.

NameDateTime takenScore ___ / 40
  1. 1.√62 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 8.2 (d) 7.9
  2. 2.Best estimate of 1363 ÷ 37? (a) 340 (b) 3400 (c) 34
  3. 3.Best estimate of 2093 ÷ 22? (a) 1050 (b) 10500 (c) 105
  4. 4.Best estimate of 2433 ÷ 49? (a) 490 (b) 4900 (c) 49
  5. 5.√86 to 1 decimal place? (a) 9.6 (b) 9.4 (c) 9.5 (d) 9.3
  6. 6.√41 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.5 (d) 6.4
  7. 7.Best estimate of 3620 ÷ 76? (a) 450 (b) 45 (c) 4500
  8. 8.Best estimate of 1275 ÷ 23? (a) 640 (b) 6400 (c) 64
  9. 9.√63 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.1 (d) 7.8
  10. 10.Best estimate of 1965 ÷ 52? (a) 39 (b) 3900 (c) 390
  11. 11.Best estimate of 2944 ÷ 34? (a) 98 (b) 9800 (c) 980
  12. 12.√75 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.4 (d) 8.5
  13. 13.√82 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 9.1 (d) 8.9
  14. 14.Best estimate of 2631 ÷ 52? (a) 530 (b) 5300 (c) 53
  15. 15.Best estimate of 2995 ÷ 47? (a) 60 (b) 6000 (c) 600
  16. 16.Best estimate of 1719 ÷ 33? (a) 5700 (b) 57 (c) 570
  17. 17.Best estimate of 2743 ÷ 46? (a) 5500 (b) 550 (c) 55
  18. 18.√66 to 1 decimal place? (a) 8.1 (b) 8.4 (c) 8.2 (d) 8.3
  19. 19.Best estimate of 973 ÷ 26? (a) 3200 (b) 32 (c) 320
  20. 20.√69 to 1 decimal place? (a) 8.1 (b) 8.3 (c) 8.2 (d) 8.0
  21. 21.Best estimate of 3121 ÷ 36? (a) 78 (b) 780 (c) 7800
  22. 22.Best estimate of 631 ÷ 43? (a) 1600 (b) 16 (c) 160
  23. 23.Best estimate of 6701 ÷ 79? (a) 8400 (b) 84 (c) 840
  24. 24.√30 to 1 decimal place? (a) 5.7 (b) 5.5 (c) 5.8 (d) 5.6
  25. 25.Best estimate of 3532 ÷ 46? (a) 71 (b) 710 (c) 7100
  26. 26.Best estimate of 4095 ÷ 46? (a) 820 (b) 8200 (c) 82
  27. 27.Best estimate of 1604 ÷ 26? (a) 5300 (b) 530 (c) 53
  28. 28.Best estimate of 697 ÷ 49? (a) 1400 (b) 140 (c) 14
  29. 29.Best estimate of 3510 ÷ 78? (a) 4400 (b) 44 (c) 440
  30. 30.√50 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 6.9 (d) 7.2
  31. 31.Best estimate of 1650 ÷ 26? (a) 550 (b) 5500 (c) 55
  32. 32.Best estimate of 4218 ÷ 87? (a) 470 (b) 47 (c) 4700
  33. 33.Best estimate of 614 ÷ 37? (a) 1500 (b) 150 (c) 15
  34. 34.√32 to 1 decimal place? (a) 5.9 (b) 5.6 (c) 5.8 (d) 5.7
  35. 35.Best estimate of 685 ÷ 27? (a) 23 (b) 230 (c) 2300
  36. 36.Best estimate of 3604 ÷ 69? (a) 510 (b) 51 (c) 5100
  37. 37.Best estimate of 921 ÷ 76? (a) 1200 (b) 12 (c) 120
  38. 38.Best estimate of 4087 ÷ 44? (a) 10200 (b) 102 (c) 1020
  39. 39.Best estimate of 1717 ÷ 42? (a) 430 (b) 4300 (c) 43
  40. 40.√92 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 9.6 (d) 9.7

Answer key

  1. 7.9
  2. 34
  3. 105
  4. 49
  5. 9.3
  6. 6.4
  7. 45
  8. 64
  9. 7.9
  10. 39
  11. 98
  12. 8.7
  13. 9.1
  14. 53
  15. 60
  16. 57
  17. 55
  18. 8.1
  19. 32
  20. 8.3
  21. 78
  22. 16
  23. 84
  24. 5.5
  25. 71
  26. 82
  27. 53
  28. 14
  29. 44
  30. 7.1
  31. 55
  32. 47
  33. 15
  34. 5.7
  35. 23
  36. 51
  37. 12
  38. 102
  39. 43
  40. 9.6

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